Initially ordered by the British Royal Navy as Sandgate Castle, the ship was transferred to Canada before completion.

Following the war, the corvette was converted for mercantile use and renamed Camosun III, then Chilcotin and Yukon Star in 1958 before being broken up in Washington in 1974.

Though the Admiralty would have preferred Loch-class frigates, the inability of many small shipyards to construct the larger ships required them to come up with a smaller vessel.

This powered one vertical triple expansion engine that drove one shaft, giving the ships a maximum speed of 16.5 knots (30.6 km/h; 19.0 mph).

[2] The ships carried 480 tons of oil giving them a range of 6,200 nautical miles (11,500 km; 7,100 mi) at 15 knots (28 km/h; 17 mph).

[4] The Type 147B was tied to the Squid anti-submarine mortar and would automatically set the depth on the fuses of the projectiles until the moment of firing.

Rather than attacking a third time, the Canadian First Lieutenant (second-in-command), Stanislas Déry, ordered the crew, "Ne tirez pas" (Don't shoot).

[8] The sinking of U-877 was another of the many submarines successfully hunted and sunk by the RCN during the Battle of the Atlantic, confirming the Canadians as leading U-boat hunters.

After the refit was completed she sailed to Esquimalt, British Columbia in July and remained there until being paid off on 22 November 1945.

[7] Following the war St. Thomas was sold into mercantile service and converted to a coastal passenger/cargo ship with a gross register tonnage of 1,835 tons.